Neutering is the surgical procedure that renders a male or female
cat or dog unable to reproduce. In males, the surgery (called castration)
entails removal of the testicles, leaving an empty scrotal sac that soon
shrinks. The testicles produce sperm and are the primary production site of the
hormone testosterone. The penis is not removed because it functions
additionally for voiding urine.

In females, surgical sterilization (commonly called spaying) involves
removal of both ovaries and the uterus by incision into the abdominal cavity.
The ovaries produce eggs at each "heat" cycle and also produce the hormones
estrogen and progesterone. The uterus is also removed because it may later
become infected if it is not removed.

These surgeries are done under general anesthesia. Pets are neutered
to prevent undesired births and a variety of medical disorders in both males
and females. Ideally, females should be neutered before their first estrus.
More pets are being neutered at younger ages so they do not contribute to
overpopulation. Speak with your veterinarian for recommendations regarding your
pet.

Effect on Sexual Behavior

Sexual behavior usually disappears
after neutering. In animals that have experienced sexual activity before
neutering, however, some sexual behavior may persist. This is not necessarily
an indication of incomplete surgical removal of the sexual organs.

Behavior that appears to be sexually motivated may be linked to other
causes. Mounting by castrated dogs, for example, is usually a sign of dominance
behavior. Masturbation, particularly in male cats and dogs, may occur following
castration. This is most common in males that have experienced sexual arousal
before castration.

For most pets, however, neutering effectively eliminates development
and progression of objectionable sexual behavior.

Effect on Aggression

Intact (unneutered) males and females
are more likely to display aggression related to sexual behavior than are
neutered animals. Fighting, particularly in males and directed at other males,
is less common after neutering.

The intensity of other types of aggression, such as dominance
aggression, is also likely to be reduced. When related to the hormonal
imbalance of false pregnancy or the agitation associated with estrus, irritable
aggression in females is eliminated by spaying. If you worry that your dog will
not protect your house after neutering, territorial aggression is not altered
by neutering.

If your pet is not intended for breeding, neutering is advised to
prevent aggressiveness related to sex hormones. Though neutering is not a
treatment for aggression, it can help minimize the severity and escalation of
aggressiveness and is often the first step toward resolving an aggressive
behavior problem. Specific diagnosis of the type of aggression displayed by
your pet, identification of the situations that trigger it, and retraining your
pet to behave differently are still essential.

Effect on General Temperament

Many pet owners are concerned
that a neutered pet will lose its vitality. Basic temperament and intelligence
are not altered by neutering. In fact, many undesirable qualities under
hormonal influence may resolve after surgery.

Your pet will not become less affectionate or playful, nor will it
resent you. You will not deprive your pet of any essential experiences. You
will, however, be acting as a responsible, informed, and loving pet owner.

The temperament of females is unlikely to improve after having a
litter. It is helpful to arrange for good homes for the litter before it
arrives. Even if you do successfully place the offspring, they will take the
place of pets awaiting adoption at pet shelters that are deprived of a chance
to be rescued.

There is no benefit from sexual activity for male or female dogs or
cats. Do not project your own physical or emotional needs onto your pet. It is
not "unnatural" to control a pet's reproductive activity by having it neutered.
Rather, it is unkind not to neuter a pet.

Effect on Escape and Roaming

A neutered pet is less likely to
roam. Castrated male dogs and cats tend to patrol smaller outdoor areas and are
less likely to engage in territorial conflicts with rivals. Spayed female cats
may actually expand the territory patrolled. A pet that has already had
successful escapes will probably continue to run away after it is
neutered.

Effect on Inappropriate Elimination

Dogs and cats may urinate
or defecate in undesirable areas of your home to stake territorial claims,
relieve anxiety, and advertise reproductive status. This may continue long
after the initial cause has passed.

Because this behavior is only partly under hormonal control, male or
female pets may begin to eliminate inappropriately even after neutering.
Neutering an animal that has begun to inappropriately eliminate reduces the
urine odor of intact adults and eliminates the contribution of hormonal
factors. Unless underlying emotional or physical factors are controlled and
environmental reminders are removed, the undesirable behavior may persist
beyond neutering.

Effect on Body Weight

Because of metabolic changes that
follow neutering, some pets may gain weight. Some pets gain weight after
neutering because they are fed more by owners who feel guilty for subjecting
their pet to any discomfort and compensate with extra food treats.

Pets, like people, become less active as they mature and may gain
weight. Activity declines as a young pet matures, regardless of whether or not
it is neutered. Before the surgery, and particularly for sexually mature
individuals, energy is channelled toward reproduction. Females in heat are
often agitated and irritable, sleeping and eating less. Males may be more
reactive to stimuli in general and more acutely aware of rivals or intruders on
their territory. Neutering reduces the intensity of many behavior problems and
eliminates or prevents certain types of undesirable behavior.

After your pet is neutered, adjust its food intake to prevent
excessive weight gain. Weight gain following neutering is easily
controlled. If food intake is not decreased after neutering, a gradual weight
increase is likely. Suggested quantities on pet food packages are meant as
general guidelines.

Adjust your pet's food intake according to its physical requirements
and appearance. Weight loss requires careful monitoring by your veterinarian,
particularly in obese pets. Special weight-reducing diets are available, but
rapid weight loss is almost never advisable. Weight gain is sometimes
associated with certain medical disorders. If you believe your pet's weight
gain is out of proportion to its food intake and exercise level, consult your
veterinarian.